High probability capture of slow trigger rate acquisitions in a digital oscilloscope with variable intensity rasterization

Abstract

A new oscilloscope design improves the processing of acquired voltage-versus-time data through the efficient high speed acquisition and rasterization of such data into a form that includes multiple-bits-per-pixel intensity information. The multi-bit-per-pixel variable intensity rasterizer is optimized for maximum throughput and most efficient use of memory bandwidth. In the presence of faltering trigger rates, rasterization interruption provides a high probability of capturing the data associated with the slow triggers. Circuitry is provided to compensate for acquisition time and amplitude non-linearities. Many-bits-per-pixel intensity information is mapped into a fewer-bits-per-pixel format by a controllable transfer function that provides multiple viewing capabilities for the operator. Another mode of operation emphasizes infrequent events over commonly occurring ones using variations in brightness or color.

What is claimed is:  
     
       1. A method for maintaining rasterizer functionality in the absence of expected trigger signals, the method comprising the steps of: 
       determining an expected trigger interval;  
       starting a new acquisition process in advance of when the expected trigger interval terminates;  
       waiting for the new acquisition process to terminate during a late trigger interval that starts at the time when the expected trigger interval terminated; and  
       if the late trigger interval expires and the new acquisition process has not terminated, aborting the new acquisition process and forwarding whatever rasterization data is available.  
     
     
       2. A method for maintaining rasterizer functionality according to claim  1  wherein the aborting step comprises the steps of: 
       determining from the trigger circuit at the expiration of the late trigger interval whether a trigger has been received; and  
       if the trigger has been received, allowing the new acquisition to proceed to completion; or  
       if the trigger has not been received, aborting the new acquisition process.  
     
     
       3. A method for maintaining rasterization functionality according to claim  1  wherein the late trigger interval of the waiting step is non-uniform. 
     
     
       4. A method for maintaining rasterization functionality according to claim  2  wherein the late trigger interval of the waiting step is non-uniform. 
     
     
       5. A method for maintaining rasterization functionality according to claim  3  wherein the non-uniform late trigger interval is made to vary within a predetermined range. 
     
     
       6. A method for maintaining rasterization functionality according to claim  4  wherein the non-uniform late trigger interval is made to vary within a predetermined range. 
     
     
       7. A method for maintaining rasterization functionality according to claim  3  wherein the non-uniform late trigger interval is made to vary in a random manner within a predetermined range. 
     
     
       8. A method for maintaining rasterization functionality according to claim  4  wherein the non-uniform late trigger interval is made to vary in a random manner within a predetermined range.